1. Field of the Invention
The present invention generally related to a semiconductor device and to a method of manufacturing the same, and more particularly, to a semiconductor device having a storage node capacitor structure suitable for rendering compact a storage node which is a constituent element of a memory cell, as well as to a method of manufacturing the semiconductor device.
2. Description of the Background Art
A capacitor having a storage node as its constituent element is used for an existing memory IC, e.g., DRAM. Such a capacitor (hereinafter referred to as a xe2x80x9cstorage node capacitorxe2x80x9d) comprises a storage node formed from a base material such as polysilicon, a cell plate, and a dielectric film interposed between the storage node and the cell plate for ensuring electrical insulation therebetween. With the foregoing configuration, electric charges can be stored in the space between the storage node and the cell plate by application of a voltage.
In rendering the storage node capacitor compact, an effective measure is to ensure that the surface area of the storage node is large in relation to the occupation area of the storage node capacitor. For example, a larger surface area of the storage node can be ensured by forming the storage node into a cylindrical shape. For this reason, a structure which comprises a cylindrical storage node has already been known as the structure of the storage node capacitor.
To obtain a compact storage node capacitor having large capacitance through use of the existing structure, the storage node must be formed into a long and narrow cylindrical shape. However, the longer and narrower the cylindrical storage node, the easier the storage node tilts. For this reason, it is difficult to manufacture a compact storage node capacitor having large capacitance at a high-yield by using the existing structure.
It is a general object of the present invention to provide a novel and useful semiconductor device and a manufacturing method thereof.
A more specific object of the present invention is to provide a semiconductor device which has a storage node capacitor structure for effectively preventing a storage node from being tilted.
The above object of the present invention is achieved by a semiconductor device having a storage node capacitor structure. The semiconductor device comprises a storage node which has a vertical surface extending in the direction perpendicular to the surface of a semiconductor substrate; and a dielectric film for tilt prevention purposes which is brought into close contact with the side surface of the vertical surface and which prevents the vertical surface from tilting.
Other object of the present invention is to provide a method of manufacturing a semiconductor device having a storage node capacitor structure which effectively prevents a storage node from being tilted.
The above object of the present invention is achieved by a method of manufacturing a semiconductor device having a storage node and a dielectric film for tilt prevention purposes, wherein the storage node has a vertical surface which extends in the direction perpendicular to the surface of a semiconductor substrate, and wherein the dielectric film is brought into close contact with the side surface of the vertical surface and prevents the vertical surface from tilting. The method comprises the steps of forming in the surface of the semiconductor substrate a cylindrical space for use in forming the vertical surface through use of a dielectric film; forming in the cylindrical space the storage node having the vertical surface; and forming a dielectric film for preventing purpose which prevents the vertical surface from tilting by utilization of the dielectric film after formation of the vertical surface.
The above object of the present invention is also achieved by a method of manufacturing a semiconductor device including a storage node and a dielectric film for tilt prevention purposes, wherein the storage node has a vertical surface extends in the direction perpendicular to the surface of a semiconductor substrate and a horizontal surface extending along the surface of the semiconductor substrate, and wherein the dielectric film is brought into close contact with the side surface of the vertical surface and prevents the vertical surface from tilting. The method comprises the steps of forming the horizontal surface on the surface of the semiconductor substrate; forming a fourth dielectric layer having a given thickness from a fourth dielectric material on the horizontal surface; forming the vertical surface while being brought into close contact with the horizontal surface and the outer circumferential surface of the fourth dielectric layer; forming a fifth dielectric layer around the vertical surface from a fifth dielectric material differing from the fourth dielectric material; and eliminating the fourth dielectric layer by means of etching through use of a measure suitable for eliminating the fourth dielectric material and for conserving the fifth dielectric material.